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Table 1 Characteristics of the study population

From: Altered muscle membrane potential and redox status differentiates two subgroups of patients with chronic fatigue syndrome

 Group 1 (N = 39)Group 2 (N = 33)
Age (years)43 ± 347 ± 2
Weight (kg)64 ± 268 ± 2
Sex ratio (F/M)28/1117/16
Onset of fatigue (months)78 ± 1969 ± 14
TBARS rest (nmol/ml)1.36 ± 0.031.01 ± 0.05***
ORP (mV)165 ± 5127 ± 4***
VO2max (mlO2/min/kg)19 ± 119 ± 1
VO2max (% predicted)67 ± 363 ± 3
Maximal work rate (W)124 ± 5118 ± 7
Maximal work rate (% predicted)90 ± 383 ± 3
HR max (bpm)151 ± 3148 ± 3
Delta K+ max (mmol/l)0.42 ± 0.070.65 ± 0.07**
Handgrip strength (N278 ± 22315 ± 33
Handgrip strength (% predicted)62 ± 771 ± 7
  1. Group 1 had marked changes in M-wave amplitude and duration whereas no M-wave changes were measured in group 2. All values shown are mean ± standard deviation
  2. TBARS thiobarbituric acid reactive substance, ORP oxidation reduction potential, VO2 oxygen uptake, HR heart rate
  3. Maximal increase in plasma potassium (K+) concentration was measured at the end of exercise. Asterisks denote significant intergroup difference (**p < 0.01; ***p < 0.001)